Polyvinyl alcohol composition



Patented Oct. 1, 19 46 POIQYXINEYL *ALQQHOL COBIPGSI-TIONI'Eohaneanahgemajer,nuueyaN. .1 assignor to Re sistoflex Corporation,Belleville, N. J a corporationmfNew Yoi'k NmiDrawingzaApnlication Maya942, Serial No. 4415275 This invention relates toplastic..compositions,

and.moreparticularly.tocQmDositions.comprising polyvinylalcohol land..modifying..agentsaivhich. renderthe -c ompositioiishnormallylflexible... The

compositionsaofeth.presentiinvention are. an.im;-... 5

provement. ov.er.- known compositions of. this kind with..resnect...totheir -retention of. flexibility-pt.

sustained elevated temperatures.

Plastic. polyvinyl alcohol compositions are suitablel-fortheamakingiofmflexibleltubes,..hose,.-gasal. 10,

kets, washers, diaphr'agms, fllnis, ...sheets,'... fila'a. merits,coati-ngs. .and .th-lika -...Tli'y rareparticullarly.suitableIfor useinlthe. handling. ..of..hydro.-.. carbon fuels;.oilsi'andfiianyi.organicisolventsg by;

which thnareunaffted. 15.

It is particulailyfle'sirahl el'ihaa articles; made of suchIzompositiohs shalllretaingthehdesirable Ia flexibility throughout awideltemperature range Heretofore. .normally. flexiblelanti'cles'fsofaplastic polyizinylalcohol compositions..have-hardened,or. .2

become. brittle when subj'e'cted...to.' elevated..tem.-..- peratuites.for ,extended..periods. of.;.ti1rie,.. assfoi'a. example, inthe case ofa flexible tubing. usedatow convey.lubrica.ting.oil.i .anaenginaa''I'liemhj'eg'atbfiili .pres'entiinventionais to. im agr; alcohol ismixed *With vvatefrplasticizerm metal prove the physical pronerties.-.of.compositions. of... the' .type describedgandmparticularly,todncreaset... their ability'to withstand high temperatu'iiesivithe;vout losing. theirflexibilitym formsmaybemadei'bytmoldin'g;"extrudingrdip pingandmtherpro cedures,'fromplastieized compositions" of polyvinyl alcohol: 'Su'ch" composi--tion's may-also-contain filling; coloring and other ,m'odifyingingredients if desired. The' ternr'f p'olyvinyt alcohol? is used-hereinan'd --in the claims to"designatenot-'only generically purepolyvinylalcohol; Which'may b'obtained in-"various modificationw'butalso 'suchfpartial "derivatives" the'reofas contain a sufficientnumbenof=unsub stituted- -hydroxyl" groups as to*ren'dei-*the compoun'dsolublein' waterr" Fora fuli'e'rexplaiiatiom see Patent Nof 2,11 1,272orPaulM5'Paulsorryissued- March 1-5 1938i ,The poly'vi-nyl alco'ho'lused *in th'follo'tving examples wa one-of"medi1lmsa'-*- vinyl alcoholswhich-are *not'completely' saponifie The examples/given below containnovel com binations of ingredients, apart from the chlorides referred-to, which are'not' claimed herein asthey are the subject matter 'of-mycopen'ding-applica tion Serial -No5-34'6j150 now"Patent=No?-'2,340;866issued'-February*8, -1 9449 Aceording -tmthe present inventionrpolyvinyl" chloridei and other ingredientsjif any; to provide amateria-l 'suitable "for-working up into 'fin'ished articles by anydesired process. The metal salt is disselved inthe water and-added-tothe) other In"my Patent NoI"2,2'4"6;9l'5' I have disclosed-ingrediiits irr solution.- In tlie examples "the flexible polyvinylalcohol compositions of certain 40 metal chlorides greatly increasestheir stability and increases the duration of their flexibility atelevated, temperatures. Experiments with a large number of metal saltsresulted in the surprising discovery that unique effects were producedby chlorides of aluminum and tin.

The effectiveness of the aforementioned chlorides with differentpolyvinyl alcohol compositions has been experimentally established andthey have been found to be generally useful for increasing the durationof flexibility of such compositions at elevated temperatures. Thisefiect is referred to herein as thermostabilizing and the means'foreffecting it as thermostabilizing agents.

As is already known, flexible articles of various.

f ormula'egive mixes suitaable' ioi use' in accord ance with the processdescribed in Schnabel Patent No. 2,177,612. After mixing, theingredients are passed through rolls to form the material into strips.The temperature of the rolls may be varied within wide limits (15-90 C.)depending Example 1 A composition was prepared from the followingingredients:

Parts by weight Polyvinyl alcohol Glycero1 35 Formamide y 6 Water 40Aluminum chloride 8 3 The aluminum chloride used was AlClsfiHzO. It wasfirst dissolved in the water, admixed with the glycerol and formamideand the resulting solution was then evenly distributed in the drypowdered polyvinyl alcohol which was thereafter processed to providemolded sheet material for test purposes.

Example 2 A molded composition was formed as in Example 1 from thefollowing ingredients;

Parts by weight Polyvinyl alcohol 100 Glycerol 35 Formamide 6 Water 40Stannous chloride 8 The stannous chloride used was SnCla2HzO.

Test strips of the materials of the foregoing examples were tested fortheir resistance to sustained high temperatures by submerging them in anoil bath maintained at a temperature of 124 126 C. They were removed at24 hour intervals and bent 180 degrees around a rod of diameter, once ineach direction, and. then returned to the bath unless bending producedfracture.

Using as a basis of comparison the composition of Example 6 of my PatentNo. 2,246,915, in which the thermo-stabilizing agent was ammoniumchloride, the results were as follows: the material of Example 1 wasequal to that of said Example 6 in duration of flexibility but wassuperior to it in that the material of Example 6 blisters badly at atemperature of 150 C. while the material of Example 1 does not formblisters at that temperature; the material of Example 2 had a durationof flexibility twice as long as that of Example 6.

While-the examples give the quantity of metal chloride in each case as8%, based on the weight of the polyvinyl alcohol, the quantity may bevaried within a range of from about 3% to about for practical results.In genera1 the thermostabilizing effect increases with an increase inthe amount of the chloride. The best results with stannous chloride havebeen obtained with abou 12%, i The practical advantages of the presentinvention are many. Polyviny1 alcohol compositions have variedapplications in industry as parts of many kinds of apparatus, equipmentand machinery in the form of hose, tubing, gaskets, diaphragms,coatings, packing and the like. Such parts may be used in pumps, valves,hydraulic systems, internal combustion engines, various kinds ofmachinery, etc. In such applications it may be required that thepolyvinyl alcohol compositions withstand continued high temperatures, asfor example when parts formed from such compositions are part of thelubricating or fuel supply system of an engine. By increasin theduration of flexibility or the stability of the compositions at elevatedtemperatures, their range of usefulness is greatly increased and theyare rendered adaptable to various fields in which it has not hithertobeen practical to use them.

The invention is not limited to the detailed examples herein given byway of illustration but may be modified in various ways within thepurview of the claims.

What is claimed is;

1. A normally flexible plasticized polyvinyl alcohol compositioncontaining as a thermostabilizing agent a substance selected from thegroup consisting of the chlorides of aluminum and tin.

2. A normally flexible plasticized polyvinyl a1- cohol compositioncontaining as a thermostabilizing agent aluminum chloride.

3. A normally flexible plasticized polyvinyl alcohol compositioncontaining a thermostabilizing agent stannous chloride.

4. A normally flexible plasticized polyvinyl alcohol compositioncontaining as a thermostabilizing agent a substance selected from'thegroup consisting of the chlorides of aluminum and tin; said substancebeing present in an amount suflicient to increase the duration offlexibility at elevated temperatures. 7

5. A'normally flexible plasticized polyvinyl alcohol compositioncontaining as a thermostabilizing agent from about 3% to about 15% ofaluminum chloride, calculated on the amount of polyvinyl alcohol.

6. A normally flexible plasticized polyvinyl alcohol compositioncontaining as a thermostabilizing agent from about 3% to about 15% ofstannous chloride, calculated on the amount of polyvinyl alcohol.

CHARLES DANGELMAJER.

